Static random access memory (SRAM) is a type of volatile semiconductor memory that stores data bits using bi-stable circuitry. Bi-stable circuitry will maintain the integrity of a stored bit without refreshing. A single SRAM cell is referred to as a memory cell because the single SRAM cell stores one bit of information, represented by a logic state of two cross coupled inverters. SRAM are commonly used in integrated circuits. Embedded SRAM is popular in high speed communication, image processing and system-on-chip (SOC) applications.
Memory arrays include multiple memory cells arranged in rows and columns. In some approaches, each memory cell in a memory array includes a connection to a power supply voltage and a connection to a reference voltage. Logic signals on bit lines control reading from and writing to a memory cell. A word line controls connections of the bit lines to the cross-coupled inverters through pass gates. When the pass gates are in a non-conductive state, the memory cell floats.
As timing and voltage margins are reduced for SRAM, the timing control signal sequence of pre-charge and write driver are difficult to accurately control. If the timing of the pre-charge and write driver are not well coordinated, unnecessary power consumption or a slow writing operation may occur.